I haven't used it, primarily due to the risks involved in using Mono for business purposes. (I have no interest in discussing this.)
My latest understanding is that it's still a single-developer project with better performance on many benchmarks than Rakudo but much worse startup time and significant feature overlap. It has monthly releases but makes no promises of stability or usability across releases.
I do not (only) ask to be a smart mouth -- I'm genuinely interested in how it rates on your personal scale of production-readiness...